In rotary internal combustion engines of the type disclosed in the U.S. Patent to Wankel et al, U.S. Pat. No. 2,988,065, dated June 13, 1961, in which a multi-cornered rotor is eccentrically supported within a multi-lobed housing cavity defined by end walls and an intermediate wall having an inner trochoidal shaped surface, a sealing grid is provided to isolate each of the working chambers defined by the rotor and housing from each other and thereby achieve optimum volumetric efficiency and hence engine efficiency. The sealing grid as exemplified in the U.S. Patents to Bentele, U.S. Pat. No. 2,979,042 dated Apr. 11, 1961; Bentele, U.S. Pat. No. 3,033,180 dated May 8, 1962; Bentele, U.S. Pat. No. 3,112,870 dated Dec. 3, 1963; Jones et al, U.S. Pat. No. 3,180,563 dated Apr. 27, 1965; and Jones U.S. Pat. No. 3,400,939 dated Sep. 10, 1968, usually comprises apex seal assemblies, including apex seal pins, at each of the corners of the rotor and in each end face of the rotor, an outer seal consisting of a plurality of gas seal strips and an inner seal or oil seal ring.
It has been found that the effectiveness of the inner seal or oil seal ring is improved when subjected to gas pressure in the space behind the oil seal ring. To provide this gas pressure by increasing the clearance between each of the seal pins of the apex seal assemblies and the gas seal strips so as to effect gas leakage from the working chambers into the space defined between the gas seal strips (outer seal) and the oil seal ring (inner seal) and hence passage of the gas to the space radially inward of the oil seal ring via the space behind the oil seal ring, is not a satisfactory method of providing gas pressure behind the oil seal ring. Such method, as is suggested in the U.S. Patent to Bentele, U.S. Pat. No. 2,979,042, is unsatisfactory because it reduces the volumetric efficiency of the engine and the mean effective pressure in low-speed range and therefore results in increased fuel consumption and a lowering of engine operating efficiency.
It is therefore an object of this invention to provide, in a rotary internal combustion engine, an improved sealing grid in which the inner seals are subjected from behind to gas pressure without impairment of the operating efficiency of the engine.
Another object of the present invention is to provide, in a rotary internal combustion engine, an improved sealing grid in which gas leakage from the working chambers is controlled to intermittently effect pressurization of the space behind each of the inner seals.
A still further object of this invention is to provide in a rotary internal combustion engine, an improved sealing grid in which the mechanical biasing forces on the inner seals is supplemented by fluid pressure and wherein the possibility of sticking of the inner seal is minimized.